Major pollutants observed were the antidepressants citalopram, paroxetine, sertraline, venlafaxine, and bupropion, and their metabolites norfluoxetine and norsertraline, and the antihistamine diphenhydramine.

A team of researchers from Ramkhamhaeng University in Thailand, Khon Kaen University in Thailand, the University at Buffalo, State University of New York and SUNY Buffalo State found the drugs in the brain, livers, muscles, and gonads of a variety of fish, including steelhead, white and yellow perch, rock bass, white bass, bowfin, rudd, and smallmouth, and largemouth bass.

"Fish are receiving this cocktail of drugs 24 hours a day, and we are now finding these drugs in their brains," Diana Aga, a researcher from the University at Buffalo who helped author the study, told the International Business Times. "It is a threat to biodiversity, and we should be very concerned."

The drugs leak into rivers and lakes from sewage overflows and waste treatment plants, and fixing outdated sewage treatment plants would help reduce the scale of the issue, according to Aga.

"These plants are focused on removing nitrogen, phosphorus, and dissolved organic carbon, but there are so many other chemicals that are not prioritized that impact our environment," Aga said.

High concentrations of antidepressant ingredients and their byproducts have been found in the brains of fish in the Great Lakes, according to a study published in the journal Environmental Science and Technology.